EP2177302B1 - Method of removing layered material of a layered construction with a laser beam, with a preliminary grooving step and a removing step - Google Patents

Description

The invention relates to a method for removing layer material of a layer structure on a carrier substrate by means of laser radiation, wherein the layer structure comprises a lower and an upper electrically conductive layer and an intermediate intermediate layer, which in turn may consist of one or more layer layers, ie individual layers. In particular, it may be an intermediate layer, which under the action of the laser radiation tends to form paths with increased electrical conductivity along a corresponding processing edge, be it that the intermediate layer is initially electrically non-conductive and forms one or more electrically conductive paths therein, whether it is that the intermediate layer already has a certain electrical conductivity, which is then markedly increased along one or more such paths. An important field of application for which the invention is suitable relates to the removal of layer material in a photovoltaic multi-layer structure for the so-called edge deletion of corresponding photovoltaic modules and for the introduction of isolation trenches for structuring integrated series-connected photovoltaic modules. In this case, the intermediate layer is the layer structure between a Front and a back contact layer, which includes in particular a so-called absorber layer as a photovoltaically active layer.

The latter structuring of integrated series-connected photovoltaic modules is disclosed, for example, in the patent DE 199 34 560 B4 and the prior art cited therein. The separation trenches can be produced photolithographically, but this means a comparatively high production cost. Traditionally, therefore, the separation trenches are usually introduced mechanically by a scoring or cutting technique. However, this procedure also proves to be rather time-consuming and cost-intensive and also relatively error-prone, for example due to wear of the mechanical scoring / cutting tool. As a possible alternative to avoid these problems, the generation of the separation trenches by means of laser radiation into consideration. However, this results in a short-circuit problem in Fig. 9 is illustrated.

Fig. 9 shows in a cut-away, idealized cross-section of a relevant here part of a photovoltaic module with a multi-layer structure in conventional photovoltaic thin-film technology. On a substrate 1, for example, a transparent glass substrate, a back contact material, such as molybdenum, applied over the entire surface, which is then structured by a first patterning process in back contacts 2a, 2b, 2c for individual solar cells 3a, 3b, 3c by the back contact material along associated first structuring lines 4a, 4b is removed. Subsequently, a photovoltaically active layer, ie the absorber layer, is formed over the whole area and subdivided into adjacent, photovoltaically active layers 6a, 6b, 6c for the individual solar cells 3a, 3b, 3c by introducing associated second structuring lines 5a, 5b. The absorber layer can be made, for example, of a conventional compound semiconductor material, such as a so-called CIS or CIGS material with copper, indium and / or gallium, and also sulfur and / or Selenium, and be formed in one or more layers. Subsequently, a front contact material is applied over the whole area and subdivided by introducing third structuring lines 7a, 7b into individual front contacts 8a, 8b, 8c for the individual cells 3a, 3b, 3c. The third structuring lines 7a, 7b extend to at least the absorber layer and may optionally extend at any depth into the absorber layer, for example also as in the example shown up to the associated back contact 2a, 2b, 2c.

How out Fig. 9 The second structuring lines 5a, 5b form connecting regions in which the front contact 8a, 8b, 8c of a respective cell 3a, 3b, 3c is electrically connected to the back contact 2a, 2b, 2c of a laterally adjacent cell by means of contact contact integrated series connection of adjacent single cells 3a, 3b, 3c leads.

When the third structuring lines 7a, 7b are generated by means of laser radiation, it has been observed that short-circuit paths can occur along their edge region 9, especially in the laser radiation-influenced semiconductor material of the absorber layer 6a, 6b, 6c, for example in the case of a CIS or CIGS semiconductor material. This is attributed to the thermal input into the absorber layer semiconductor material by the laser radiation at the processing edge 9 of the third structuring lines 7a, 7b, which can lead to a conversion of the semiconductor material with the consequence of a considerable increase in its electrical conductivity. In unfavorable cases, such a short-circuit path can extend from the rear contact 2a, 2b, 2c to the front contact 8a, 8b, 8c of the respective individual cell 3a, 3b, 3c along the processing edge 9 of the respective third structuring line 7a, 7b, and thereby the solar cell 3a, 3b , 3c short circuit electrically as in Fig. 9 through a respective short-circuit surface edge region 10a, 10b of the absorber layer material on the left side of the third structuring lines 7a, 7b for the left and the middle solar cell 3a, 3b indicated by dashed lines. Although an identical electrically conductive path can also be found at the in Fig. 9 form right edge of every third patterning line 7a, 7b, but this is harmless, as here anyway an electrically conductive connection between back contact of one cell and front contact of the adjacent cell due to the second structuring lines 5a, 5b filling front contact layer material for series connection of the cells 3a, 3b, 3c present.

An analog short-circuit problem can occur in the so-called stripping of such photovoltaic modules by means of laser radiation. In this stripping, a marginal portion, or other portion of the multilayer structure, is removed over the substrate, including the absorber layer and the front contact layer, to form there e.g. To attach a module enclosure or module encapsulation or divide a module into several separate sub-modules on a common substrate.

The publication DE 10 2004 016 313 A1 discloses a method and apparatus for making single cells from a flexible tape previously provided with a solar cell layer throughout, wherein edge portions are severed by scribing in the longitudinal direction of the tape and transverse intersections of the tape by a double scribe before the tape mechanically or mechanically is cut into individual cells by laser cutting in the area between the double scribe. The scratching is intended to prevent short circuits between the back contact layer and the transparent front contact layer of the solar cell strip, for example due to remaining metal chips or excess front contact layer material. In this case, the scribe is introduced through the transparent front contact layer, care being taken that it does not extend completely through the underlying absorber layer so as not to run the risk of that back contact layer material is evaporated and thereby undesirable short circuits occur.

The publications US 2006/0266409 A1 which is considered the closest prior art, WO 2008/050556 A1 and JP 2008-066453 A each disclose a thin film solar cell layer structure in which a transparent front contact layer, an absorber layer and a back contact layer are successively applied to a transparent carrier substrate. For the purpose of edge deletion, an auxiliary trench, which extends through the back contact layer and the entire absorber layer, is first introduced by irradiating from the substrate side with a laser radiation primarily heating the absorber layer material, whereby the absorber layer material is heated in the irradiated area and vaporizes while also pulling away the overlying back contact layer material. In a subsequent removal step, in turn, from the substrate side is irradiated with a different laser radiation, which primarily heats the material of the transparent front contact layer, whereby this evaporates and the overlying material of the absorber layer and the back contact layer with removed.

The invention is based on the technical problem of providing a method with which the layer material of the above-mentioned layer structure with the two electrically conductive layers and the intermediate layer by means of laser radiation with comparatively little effort and reliable, avoiding short-circuit paths in the intermediate layer from one to the other electrically conductive layer just for the mentioned applications of stripping and Trenngrabenstrukturierung of photovoltaic modules can be removed.

The invention solves this problem by providing a Schichtmaterialabtragverfahrens with the features of claim 1. In this method, an auxiliary step is performed prior to the actual Abtragschritt in which the layer material is ablated in a predetermined Sollabtraglinienbereich by laser radiation, along at least one side of Sollabtraglinienbereichs an auxiliary trench is introduced into the layer material. In this case, the auxiliary trench is introduced directly after the side edge of the Sollabtraglinienbereichs or with a certain predetermined lateral distance from this.

This has the consequence that after performing the Abtragschritts not only the material is removed in the Sollabtraglinienbereich to the desired depth there, but also the layer material in the lateral auxiliary trench up to the specifiable depth for selbige, including any layer material in the narrow range between the Sollabtraglinienbereich and the auxiliary trench when the latter is introduced at a slightly lateral distance from the Sollabtraglinienbereich. The auxiliary trench in the removal step can act as a predetermined breaking line along which the be removed layer material at least the upper electrically conductive layer, for example, the front contact layer of a photovoltaic multi-layer structure, can be blasted off in a controlled manner, so that the upper electrically conductive layer relative to the processing edge of the intermediate view is reliably electrically isolated. As a result of the removal step, the layer material is typically removed at most to the carrier substrate, ie the latter is not severed by the removal step in this case.

In the mentioned applications of edge deletion and separation trench generation for photovoltaic modules, this avoids the described short circuit problem, since the front contact layer is laterally spaced from the short-circuit endangered absorber layer processing edge of the structuring lines concerned by the auxiliary trench generated and thereby remains electrically isolated from this. In addition, the auxiliary trench generated can contribute to facilitated removal of the layer material in the removal step, which is especially true for an improved removal of the front contact surface layer in the case of photovoltaic modules mentioned.

In one embodiment of the invention according to claim 2, the auxiliary trench is introduced to a depth which is smaller than a removal depth in the subsequent removal step. Such auxiliary excavation depth is sufficient for many applications to provide a suitable predetermined breaking line for the subsequent removal step, while minimizing the effort for auxiliary trench production. A small auxiliary excavation depth, which may well be smaller than the thickness of the upper electrically conductive layer, also has the advantage that when using laser radiation to generate the auxiliary trench excessive exposure of the laser radiation to the intermediate layer with the risk of forming corresponding shorting paths in this Process step can be avoided. Alternatively, for appropriate applications be provided to select the auxiliary trough depth substantially equal to the Abtragtiefe for during the Abtragschritts to be removed in the Sollabtraglinienbereich layer material.

In a further embodiment of the invention, according to claim 3, an auxiliary trench is generated along each of the two side regions of the Sollabtraglinienbereichs, so that a predetermined breaking line is predetermined on both sides, if the layer material is removed by laser radiation in the intermediate Sollabtraglinienbereich by the subsequent Abtragschritt by it by the laser radiation effect evaporated and / or blasted off.

In a development of the invention according to claim 4, the auxiliary trench is introduced by means of laser radiation. This can be compared with an alternative possible introduction, e.g. reduce the manufacturing effort by a mechanical process. In one embodiment of this variant of the method according to claim 5, a different laser radiation than in the removal step is selected for introducing the auxiliary trench. Thus, the laser radiation can be optimized in each case on the introduction of the auxiliary trench or on the Schichtmaterialabtrag in the subsequent Abtragschritt out.

A development according to claim 6 is directed to an application of the invention for Trenngrabenstrukturierung in the production of an integrated series-connected photovoltaic module. According to the invention, the cell-dividing separating trenches can be produced with relatively little effort by means of laser radiation, short-circuit problems being prevented by the prior introduction of the auxiliary trench.

A development according to claim 7 is directed specifically to an application of the invention for edge-side or non-edge removal of a photovoltaic module multilayer structure on a Substrate, whereby the implementation effort by the use of laser radiation can be kept relatively low and by the auxiliary trench short-circuit problems are avoided and the removal of material in the removal step is facilitated.

In one embodiment of the invention according to claim 8, the laser radiation is irradiated in the removal step from a back side of the photovoltaic module substrate, which may be advantageous in certain cases, e.g. with regard to arranging the entire process apparatus, with regard to the process sequence of auxiliary step and removal step and / or with regard to removal behavior of the layer material to be removed.

In one embodiment of the invention according to claim 9, the laser radiation for the removal step is selected for the mentioned applications in photovoltaic modules, that results in a high laser radiation absorption in the photovoltaically active layer at the same time at most weak absorption by the front contact layer.

In a development of the invention according to claim 10, the auxiliary trench is introduced by means of laser radiation for the applications mentioned in photovoltaic modules whose parameters are optimized for high near-surface absorption by the front contact layer, in particular in terms of wavelength and / or power density or pulse duration, at the same time if necessary, the laser radiation can be adjusted so that the underlying absorber layer is not significantly affected by the auxiliary trench generating laser radiation.

Fig. 1

eine teilweise, idealisierte Querschnittansicht eines erfindungsgemäßen Photovoltaikmodul-Mehrschichtaufbaus,

Fig. 2

ein Flussdiagramm zur Erläuterung eines erfindungsgemäßen Verfahrens zur Herstellung des Mehrschichtaufbaus von Fig. 1,

Fig. 3

eine Querschnittansicht eines vorgefertigten Photovoltaik-Mehrschichtaufbaus vor Durchführung eines erfindungsgemäßen Hilfsschritts gemäß Fig. 2,

Fig. 4

die Ansicht von Fig. 3 nach Durchführen des Hilfsschritts,

Fig. 5

eine photographische Draufsicht auf einen erfindungsgemäß hergestellten Photovoltaik-Mehrschichtaufbau nach Art von Fig. 1,

Fig. 6

eine teilweise, idealisierte Querschnittansicht eines Photovoltaik-Mehrschichtaufbaus in einem Randbereich vor Durchführen eines erfindungsgemäßen Hilfsschritts,

Fig. 7

die Ansicht von Fig. 6 nach Durchführen des Hilfsschritts,

Fig. 8

die Ansicht von Fig. 7 nach Durchführen eines Abtragschritts und

Fig. 9

eine teilweise, idealisierte Querschnittansicht eines konventionell hergestellten Photovoltaik-Mehrschichtaufbaus mit Trenngrabenstrukturierung zwecks integrierter Serienverschaltung.

Advantageous, described below embodiments of the invention and the above for their better understanding explained, conventional Embodiments are illustrated in the drawings, in which:

Fig. 1

a partial, idealized cross-sectional view of a photovoltaic module multilayer structure according to the invention,

Fig. 2

a flowchart for explaining a method according to the invention for producing the multi-layer structure of Fig. 1 .

Fig. 3

a cross-sectional view of a prefabricated photovoltaic multilayer structure before carrying out an auxiliary step according to the invention according to Fig. 2 .

Fig. 4

the view of Fig. 3 after performing the auxiliary step,

Fig. 5

a photographic plan view of a photovoltaic multilayer structure according to the invention produced in the manner of Fig. 1 .

Fig. 6

a partially, idealized cross-sectional view of a photovoltaic multi-layer structure in an edge region before performing an auxiliary step according to the invention,

Fig. 7

the view of Fig. 6 after performing the auxiliary step,

Fig. 8

the view of Fig. 7 after performing a removal step and

Fig. 9

a partial, idealized cross-sectional view of a conventionally produced photovoltaic multilayer structure with Trenngrabenstrukturierung for the purpose of integrated serial connection.

In Fig. 1 is idealized a here interesting part of a photovoltaic layer structure according to the invention in a cross-sectional view accordingly Fig. 9 for the sake of simplicity, identical reference numerals are used for identical and functionally equivalent elements and in this respect to the above description Fig. 9 can be referenced. Unlike the conventional example of Fig. 9 is in the multi-layer structure of the invention Fig. 1 in each of the series-connected solar cells 3a, 3b, 3c, an auxiliary trench 11a, 11b is present, which is introduced before the introduction of the patterning separating trenches, ie the third patterning lines 7a, 7b, in the still continuous front contact layer. In this case, the auxiliary trenches 11a, 11b in the example shown on one side, in Fig. 1 the left side of a respective Sollabtraglinienbereichs, which is defined by the lateral position and dimension of the patterning separation trenches 7a, 7b.

How out Fig. 1 to recognize, the inventive measure of introducing the auxiliary trenches 11a, 11b has the consequence that compared with the conventional example of Fig. 9 an additional part of each front contact 8a, 8b, 8c above the in Fig. 1 left processing edge 9 of the introduced through the front contact layer 8a, 8b, 8c and the absorber layer 6a, 6b, 6c through separation trenches 7a, 7b is removed. Therefore, even if a short-circuit path 10a, 10b arises at this processing edge 9 of the absorber layer 6a, 6b, 6c during the generation of the separation trenches 7a, 7b by means of suitable laser radiation, a short circuit between back contact 2a, 2b, 2c and front contact 8a, 8b, 8c of FIG respective solar cell 3a, 3b, 3c reliably avoided by the associated front contact 8a, 8b, 8c a predetermined by the auxiliary trench 11a, 11b lateral distance to this processing edge 9 or to the possibly formed there, short-circuiting zone 10a in the semiconductor material of the absorber layer 6a, 6b, 6c complies.

The Fig. 2 to 4 illustrate the part of the invention for multilayer construction of Fig. 1 leading manufacturing process. A starting step 12 involves the provision of a precursor of conventional type, as disclosed in US Pat Fig. 3 is shown. In a subsequent auxiliary step 13, the auxiliary trenches 11a, 11b are then introduced into the front contact layer 8, as in FIG Fig. 4 illustrated. Each auxiliary trench 11a, 11b is along one side, in Fig. 4 the left side, a Sollabtraglinienbereich T introduced, which is defined by the lateral position of the later to be introduced separation trenches. In this case, the auxiliary trenches 11a, 11b are introduced without or alternatively with a predeterminable lateral distance to the respective Sollabtraglinienbereich T and up to a predeterminable auxiliary excavation depth, which is suitably selected depending on the needs and application. In the example shown by Fig. 4 According to the invention, the auxiliary groove depth is equal to the thickness of the front contact layer 8, ie the auxiliary trenches 11a, 11b extend through the front contact layer 8 to the top of the absorber layer 6a, 6b, 6c. In alternative embodiments, the respective auxiliary trench extends even to a certain depth less than the front contact layer thickness in the front contact layer or with a relation to the front contact layer thickness slightly greater depth even slightly into the absorber layer 6a, 6b, 6c inside.

In a subsequent removal step 14, the separation trenches 7a, 7b are generated by irradiating suitable laser radiation into the target removal line region T of each cell 3a, 3b, 3c, so that the layer material of the front contact layer 8 and the underlying absorber layer 6a, 6b, 6c located there is evaporated by evaporation and / or blowing off is removed. At the end of 15 this process step then lies the photovoltaic multilayer structure with in Fig. 1 structure shown before. Although in the example shown the separation trenches 7a, 7b are introduced through the absorber layer 6a, 6b, 6c to the back contact layer 2a, 2b, 2c, the separation depth is not critical as long as it reliably removes the front contact layer material in the target removal line region T of each cell 3a, 3b, 3c and thus the division of the front contact layer 8 in the separate front contacts 8a, 8b, 8c guaranteed. In other words, even a depth for the separating trenches 7a, 7b which is equal to the front contact layer thickness or extends into the absorber layer 6a, 6b, 6c without completely penetrating the back contact layer 2a, 2b, 2c may already be sufficient. Precise control of the separation trench thickness is therefore not mandatory as long as it is ensured that it is at least equal to the front contact layer thickness. The introduction of the separation trenches 7a, 7b as shown through the entire absorber layer thickness through to the front contacts 2a, 2b, 2c may be expedient, for example, in cases where there is a need to reduce the transverse conductivity of the absorber layer 6a, 6b, 6c.

The auxiliary trenches 11a, 11b introduced in accordance with the invention act as respective predetermined breaking line in the removal step in which the separation trenches are generated, along which the front contact layer can break off in a controlled manner and can therefore be blasted off in the target removal line region and optionally in the region laterally between auxiliary trench and target removal line region. The auxiliary trench 11a, 11b ensures sufficient mechanical weakening of the front contact layer 8 in the corresponding region, for which even an auxiliary trench depth smaller than the front contact layer thickness can be sufficient. The action of the laser radiation in the subsequent removal step results in strong local heating and volume expansion of the local layer material and in particular of the absorber layer material within the target removal line region T, which is an upward or outward force caused on the front contact surface layer in this area. Due to the mechanical weakening of the front contact layer 8 due to the introduced auxiliary trenches 11a, 11b, the detachment or blasting off of the front contact layer in the target removal line region is made possible with a comparatively low required detaching force and in a region precisely defined by the auxiliary trenches 11a, 11b.

The respective auxiliary trench 11a, 11b may be introduced by any suitable technique. This includes mechanical and photolithographic methods as well as the possibility of introducing the auxiliary trench 11a, 11b by means of laser radiation, the laser radiation parameters being suitably selected in order to meet the different requirements of the trench generation in the subsequent removal step. In particular, the laser beam characteristic is adjusted to a comparatively near-surface energy input in order to produce the auxiliary trenches 11a, 11b, without interfering with the underlying semiconductor material of the absorber layer 6a, 6b, 6c. For this example, laser radiation can be used with a wavelength for which the contact layer material has a high absorption. For a ZnO material, as it is often used as a front contact layer material, for example, laser radiation with wavelengths in the range of about 355 nm or less or with a wavelength above about 1500 nm can be used. Additionally or alternatively, to achieve near-surface absorption, relatively high power density laser radiation can be used using a pulsed short-pulse laser. In particular, the pulse duration is selected to be so short that no appreciable disturbing heat input into the semiconductor material of the absorber layer 6a, 6b, 6c takes place by heat conduction during a particular pulse. Another advantage of laser radiation with short intense laser pulses is the sudden local thermal expansion and explosive evaporation of the front contact layer material in the auxiliary trench area caused thereby. The mechanical forces induced thereby can lead to the formation of fine longitudinal and transverse tears in the front contact layer material, which facilitates the subsequent breaking of the same into smaller pieces during the break-off in the subsequent removal step. A disturbing influence of the laser radiation on the absorber layer or more generally on the intermediate layer between upper electrically conductive layer, here the front contact layer, and lower electrically conductive layer, here the back contact layer, can also be avoided during auxiliary trench generation in that the auxiliary trench depth is smaller than the thickness the upper electrically conductive layer is held, that is, the auxiliary trench only in the upper electrically conductive layer, but not completely introduced therethrough to the intermediate layer.

In a corresponding variant of the method with respect to the removal step 14, laser radiation having a wavelength which is selected so that the laser radiation in the front contact layer is not appreciably absorbed yet, but only in the underlying absorber layer semiconductor material is used for the separation trench generation. A relatively high pressure then results due to evaporating absorber material under the front contact layer which is still closed at the beginning of the removal step in the target removal line region T, which advantageously generates a high force development for breaking off the superficial front contact layer in the target removal line region.

In the example shown, the respective auxiliary trench 11a, 11b connects directly, ie without lateral spacing, to the target removal line region T, which represents the position and width of the dividing trench to be introduced. Alternatively, it is also possible to introduce the auxiliary trench with a slightly lateral distance to the Sollabtraglinienbereich. The intermediate front contact layer material is then in the subsequent removal step in this narrow intermediate area between auxiliary trench and Sollabtraglinienbereich reliably blasted off. The auxiliary trench thus serves to set the Absprengbereich the front contact layer material in Abtragschritt as a predetermined breaking line directly to the side of the Sollabtraglinienbereichs or with a slight distance thereof, ie the lateral distance of the remaining front contact 8a, 8b, 8c from the facing processing edge 9 of the separation trench 7a, 7b Fig. 1 ,

Fig. 5 shows a top view of a microscopic image of a process according to the invention processed photovoltaic multilayer structure. In an upper portion 16 and a lower portion 17 of Fig. 5 in each case the unchanged surface of the front contact layer 8 can be seen. Subsequent to the lower region 17, a lower part 11 'of an auxiliary trench introduced into the front contact layer material can still be seen. Subsequent to the upper section 16 is in Fig. 5 to recognize a Abtragspurbereich 18 from edge zone 18a and actual Abtragspur 18b, which represents the introduced, structuring separation trench of the associated solar cell. A middle area 19 of Fig. 5 represents a zone with blasted front contact material, thus the front contact layer material of a solar cell in the lower portion 17 of FIG Fig. 5 sufficiently spaced from Trenngrabenbereich 18 of the same solar cell and thus reliably kept electrically isolated. For example, the distance between the center of the auxiliary track and the center of the removal track may typically be a few 10 μm, for example about 40 μm. In the right part of Fig. 5 is still a blasted front contact layer particle 20 to recognize, which is located in an elevated position and is therefore shown out of focus.

The Fig. 6 to 8 illustrate as a further possible application of the invention a realized using the Schichtmaterialabtragverfahrens invention edge deletion for a photovoltaic multilayer structure in the manner of Fig. 1 , First, again, an intermediate product corresponding Fig. 3 made, with in the edge region shown unstructured back contact layer 2 and absorber layer 6, as in Fig. 6 illustrated. In this case, an edge stripping of the layer structure over the substrate 1 within a predeterminable edge zone width R is to be undertaken. For this, first, as in Fig. 7 illustrates an auxiliary trench 21 along the inner side of the demarcated edge zone R introduced into the front contact layer 8, with a certain predetermined distance A from the edge zone R, including the above explained to the auxiliary trenches 11a, 11b for the trench generation techniques in the same way are usable.

Subsequently, the layer material in the edge zone region R is removed above the substrate 1 in the corresponding removal step by means of laser radiation, whereby the front contact layer material between the edge zone region R and the auxiliary trench 21 is blasted off. Fig. 8 shows the product thus obtained with stripped edge zone R. By the breaking off of the front contact layer material in the region between edge zone R and auxiliary trench 21, where it is also removed in the region of the auxiliary trench 21 itself, the front contact layer 8 does not extend to the peripheral edge of the front contact layer 2 and the absorber layer 6, but ends with a lateral distance in front of this. Therefore, even in this application, a short circuit between the front contact layer 8 and the back contact layer 2 is reliably avoided, even if an electrically conductive short-circuit path 10c corresponding to the short-circuit paths 10a, 10b is formed by the layer removal process along the peripheral edge of the absorber layer 6 in the above-described separation trench structure, as in FIG Fig. 8 indicated by dashed lines.

In the stratified removal step, the laser radiation can be irradiated from the front, ie from the front contact layer, or alternatively from the rear, ie from a substrate rear side, as required and in case of application be, ie in Fig. 7 from underneath. In contrast, the introduction of the auxiliary trench 21 takes place also in the case of edge deletion from the front, ie directly on the surface front contact layer 8. In corresponding embodiments, the removal of the layer material in the edge region R can be carried out in a same process run with the introduction of the auxiliary trench 21, to which only the laser radiation for introducing the auxiliary trench 21 in the machining direction with a suitable lead in front of the front or rear for removing the layer material in the edge region R irradiated laser radiation is performed. This quasi-simultaneous and only slightly offset locally implementation of the auxiliary step for introducing the respective auxiliary trench and the Abtragschritts for removing the layer material in the appropriate Sollabtraglinienbereich is equally suitable for other variants of the method, in particular for Trenngrabenstrukturierung according to the Fig. 1 to 4 ,

In the same way as explained above using the example of edge deletion, another, in particular line-shaped, non-edge-side region of a photovoltaic multilayer structure can be stripped on a substrate, in which case two auxiliary trenches are preferably provided on both sides of the line-shaped region to be stripped. For example, such a non-edge-side stripping can be used to divide a module into a plurality of separate submodules on a common substrate.

While in the embodiments shown an auxiliary trench is introduced only on one side of the Sollabtraglinienbereichs, the invention includes in the same way also embodiments in which a respective auxiliary trench along both longitudinal sides of the Sollabtraglinienbereichs is introduced. This is expedient in cases where there is a need to limit and / or assist the material removal in the target removal area on both sides, for example in the case a non-edge removal of a photovoltaic multilayer structure on a substrate

Although the embodiments shown relate to the trench structuring and edge deletion of a photovoltaic multilayer structure, it is to be understood that the invention is equally applicable to other applications in photovoltaic modules and any other devices in which layer material of a layered construction on a carrier substrate having a lower and an upper electrically conductive layer and an intermediate, single or multi-layer intermediate layer includes, defined by laser radiation to be removed in a predetermined lateral area. In this case, the invention enables a reliable avoidance of electrical short-circuit paths, especially in cases in which the interlayer material tends to form such short-circuit paths under the action of the laser radiation.

Claims (10)

1. A method for removing layered material of a layered structure on a support substrate (1) in a predetermined removal line region (T, R), the layered structure including a lower (2a, 2b, 2c; 2) and an upper electrically conductive layer (8a, 8b, 8c; 8) and interposed between them a monolayer or multilayer intermediate layer material (6), comprising the following steps:

   - an auxiliary step (13), wherein along at least one side of the predetermined removal line region an auxiliary trench (11a, 11b, 21) is formed in the layered material of at least the upper electrically conductive layer (8a, 8b, 8c; 8) down to a depth in the layered structure that is equal to or smaller than the thickness of the upper electrically conductive layer (8a, 8b, 8c; 8) or that is greater than the thickness of the upper electrically conductive layer (8a, 8b, 8c; 8) and yet reaching into the intermediate layer material (6) to a minor extent, and

   - a removal step (14), wherein laser radiation is irradiated onto the layered material in the predetermined removal line region laterally adjacent to the auxiliary trench (11a, 11b, 21) in such a manner that layered material located in the predetermined removal line region is removed at least in the thickness of the upper electrically conductive layer (8a, 8b, 8c; 8),

   - wherein by means of the removal step the layered material is removed at most down to the support substrate (1) and/or wherein the auxiliary trench (11 a, 11 b, 21) is formed with a predefined lateral distance (A) to the predetermined removal line region and during the removal step serves as a predetermined break line for electrically insulating fragmentation of layered material of the upper electrically conductive layer (8a, 8b, 8c; 8) at least in the region located laterally between the auxiliary trench (11a, 11b, 21) and the predetermined removal line region by means of laser radiation.
2. The method according to claim 1, further characterized in that the auxiliary trench (11 a, 11 b, 21) is formed down to a depth that is smaller than a removal depth of the layered material in the predetermined removal line region during the removal step (14).
3. The method according to claim 1 or 2, further characterized in that in each case one auxiliary trench (11 a, 11 b, 21) is formed along each of two opposed sides of the predetermined removal line region during the auxiliary step (13).
4. The method according to any of claims 1 to 3, further characterized in that the auxiliary trench (11 a, 11 b, 21) is formed by means of laser radiation.
5. The method according to claim 4, characterized in that the auxiliary trench (11 a, 11 b, 21) is formed by means of a laser radiation which in terms of wavelength and/or power density and/or pulse length is different from the laser radiation during the removal step (14).
6. The method according to any of claims 1 to 5, further characterized in that the upper electrically conductive layer (8) is a front contact layer of a photovoltaics multilayer structure on the support substrate and the predetermined removal line region is a separating trench (7a, 7b) formed at least through the front contact layer.
7. The method according to any of claims 1 to 6, further characterized in that the predetermined removal line region is a region to be delaminated of a photovoltaics multilayer structure on the support substrate (1), wherein the upper electrically conductive layer is a front contact layer (8) of the photovoltaics multilayer structure and the monolayer or multilayer intermediate layer material includes an absorber layer (6) of the photovoltaics multilayer structure.
8. The method according to any of claims 1 to 7, further characterized in that during the removal step the laser radiation is irradiated from a rear side of the support substrate.
9. The method according to any of claims 6 to 8, further characterized in that during the removal step (14) the laser radiation is irradiated using a wavelength that is preselected selectively for absorption by the absorber layer.
10. The method according to any of claims 6 to 9, further characterized in that during the auxiliary step the laser radiation is preselected selectively for absorption in the front contact layer.

Images